drm/xe/engine: add missing rpm for bind engines

Bind engines need to use the migration vm, however we don't have any rpm
for such a vm, otherwise the kernel would prevent rpm suspend-resume.
There are two issues here, first is the actual engine create which needs
to touch the lrc, but since that is in VRAM we trigger loads of missing
mem_access asserts. The second issue is when destroying the actual
engine, which requires GuC CT to deregister the context.

v2 (Rodrigo):
  - Just use ENGINE_FLAG_VM as the indicator that we need to hold an rpm
    ref. This also handles the case in xe_vm_create() where we create
    default bind engines.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/499
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/504
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

diff --git a/drivers/gpu/drm/xe/xe_engine.c b/drivers/gpu/drm/xe/xe_engine.c
index 71f77878522675d2b01d79f1306ca30c1228e412..f60d29b2b5066cec237cef94754dada380d19422 100644 (file)
--- a/drivers/gpu/drm/xe/xe_engine.c
+++ b/drivers/gpu/drm/xe/xe_engine.c
@@ -76,6 +76,17 @@ static struct xe_engine *__xe_engine_create(struct xe_device *xe,
        if (err)
                goto err_lrc;
 
+       /*
+        * Normally the user vm holds an rpm ref to keep the device
+        * awake, and the context holds a ref for the vm, however for
+        * some engines we use the kernels migrate vm underneath which
+        * offers no such rpm ref. Make sure we keep a ref here, so we
+        * can perform GuC CT actions when needed. Caller is expected to
+        * have already grabbed the rpm ref outside any sensitive locks.
+        */
+       if (e->flags & ENGINE_FLAG_VM)
+               drm_WARN_ON(&xe->drm, !xe_device_mem_access_get_if_ongoing(xe));
+
        return e;
 
 err_lrc:
@@ -152,6 +163,8 @@ void xe_engine_fini(struct xe_engine *e)
                xe_lrc_finish(e->lrc + i);
        if (e->vm)
                xe_vm_put(e->vm);
+       if (e->flags & ENGINE_FLAG_VM)
+               xe_device_mem_access_put(gt_to_xe(e->gt));
 
        kfree(e);
 }
@@ -560,6 +573,9 @@ int xe_engine_create_ioctl(struct drm_device *dev, void *data,
                        if (XE_IOCTL_DBG(xe, !hwe))
                                return -EINVAL;
 
+                       /* The migration vm doesn't hold rpm ref */
+                       xe_device_mem_access_get(xe);
+
                        migrate_vm = xe_migrate_get_vm(gt_to_tile(gt)->migrate);
                        new = xe_engine_create(xe, migrate_vm, logical_mask,
                                               args->width, hwe,
@@ -568,6 +584,9 @@ int xe_engine_create_ioctl(struct drm_device *dev, void *data,
                                               (id ?
                                               ENGINE_FLAG_BIND_ENGINE_CHILD :
                                               0));
+
+                       xe_device_mem_access_put(xe); /* now held by engine */
+
                        xe_vm_put(migrate_vm);
                        if (IS_ERR(new)) {
                                err = PTR_ERR(new);

diff --git a/drivers/gpu/drm/xe/xe_engine_types.h b/drivers/gpu/drm/xe/xe_engine_types.h
index a0cd80cb9d7b1cc32cabe45499ff09fdc71f3dc5..f1d531735f6d22d97a462b3cc36954739a342aee 100644 (file)
--- a/drivers/gpu/drm/xe/xe_engine_types.h
+++ b/drivers/gpu/drm/xe/xe_engine_types.h
@@ -69,6 +69,7 @@ struct xe_engine {
 #define ENGINE_FLAG_KERNEL             BIT(1)
 #define ENGINE_FLAG_PERSISTENT         BIT(2)
 #define ENGINE_FLAG_COMPUTE_MODE       BIT(3)
+/* Caller needs to hold rpm ref when creating engine with ENGINE_FLAG_VM */
 #define ENGINE_FLAG_VM                 BIT(4)
 #define ENGINE_FLAG_BIND_ENGINE_CHILD  BIT(5)
 #define ENGINE_FLAG_WA                 BIT(6)